Definition television systems

Abstract

A receiver-compatible EDTV system wherein enhancement information is adaptively modulated to suppress channel noise and is transmitted outside the usable picture area of a receiver compatible signal of the receiver compatible EDTV system.

What is claimed is: 
     
       1. A receiver-compatible EDTV system comprising means for adaptively modulating an enhancement signal so as to suppress channel noise and means for transmitting the adaptively-modulated enhancement signal as part of a receiver-compatible signal and outside the usable picture area of the receiver-compatible EDTV system but within at least a portion of the usable picture area of an NTSC system, said receiver-compatible signal carrying an EDTV aspect ratio image. 
     
     
       2. The system of claim 1 further comprising means for increasing effective bandwidth at the expense of signal-to-noise ratio by superimposing a reduced amplitude enhancement signal on a multilevel digital signal, said reduced-amplitude enhancement signal being derived from the adaptively-modulated enhancement signal. 
     
     
       3. The system of claim 1 further comprising a receiver compatible with said enhanced-definition television system, said receiver comprising compatible front-end circuitry for selecting and demodulating the received RF signal to produce a video signal, compatible processing circuitry for processing the video signal to produce display data, and display circuitry to display said data on a display device. 
     
     
       4. The system of claim 1 wherein the enhancement signal is placed within bar areas located at the top and/or bottom of the usable picture area of the NTSC system. 
     
     
       5. The system of claim 1 wherein said high frequency information lies outside a block of frequency space, said block having the dimensions of about 425 samples per width by 240 lines per height by 12 frames per second.